My first thought was "in the Python language", but it's a C extension. Is it even possible to write crypto code in memory managed languages? Due to the need for everything to run in constant time.

IIRC Go has pretty decent crypto implemented in Go: https://pkg.go.dev/crypto

Plenty of cryptography in Java, C# and Go.

rust is a type of memory managed language and I don't see any issue with writing crypto there?

c++ is a (poorly) memory managed language by that logic (std::unique_ptr, etc)